The proposed research is designed to test and extend general models of the serial order of behavior. The models are hierarchical in nature and deal mainly with the perception and production of serially ordered phonemes, syllables and morphological components of words. The models make specific predictions concerning speech errors, speech rate, and reaction times for perceiving and producing phonemes, syllables and words of varying degrees of phonological, syllabic and morphological complexity and experiments are proposed to test these predictions. Comparisons of serial order errors in two different motor systems (speech and finger movements) will test the generality of the models. The proposed research also examines the possibility that derivational rules play a role in the perception and production of complex nouns such as GOVERNMENT. Research on a developmental hypothesis concerning the nature of serial processes in reading of children and adults is also proposed. The proposed research also deals with pathological aspects of sequential behavior, including stuttering and other speech disorders as well as naturally occuring errors and proposes a new model of everyday psychopathology.